Benchmark: UInt8Array vs cast to array index access

Script Preparation code:

let arr = [];
for (let i = 0; i < 100000; i++)
    arr.push(i % 256);

var u8a = new Uint8Array(arr);

Tests:

Uint8Array index
const a = u8a; //(u8a as unknown) as number[]; const al = a.length; let s = 0; for(let i=0; i<al; i++) s += a[i];
Array.from array index
const a = Array.from(u8a); const al = a.length; let s = 0; for(let i=0; i<al; i++) s += a[i];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Uint8Array index
Array.from array index

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The benchmark is designed to compare two approaches for accessing elements in a `Uint8Array`:

1. Direct access using the `[]` notation (e.g., `a[i]`)
2. Using the `Array.from()` method to convert the `Uint8Array` to an array, and then accessing elements using the array's indexing syntax (e.g., `a[i]`)

**Benchmark Preparation Code**

The script preparation code generates a large array of 100,000 unsigned 8-bit integers (`Uint8Array`) and stores it in the variable `u8a`. This array will be used as the input for both benchmark test cases.

**Individual Test Cases**

There are two test cases:

1. **`Uint8Array index`**
```javascript
const a = u8a; // (u8a as unknown) as number[];
const al = a.length;
let s = 0;
for(let i=0; i<al; i++) {
  s += a[i]; // direct access using [] notation
}
```
This test case directly accesses the elements of `u8a` using the `[]` notation. The variable `s` accumulates the sum of all elements.

2. **`Array.from array index`**
```javascript
const a = Array.from(u8a);
const al = a.length;
let s = 0;
for(let i=0; i<al; i++) {
  s += a[i]; // accessing elements using Array.from()
}
```
This test case converts `u8a` to an array using `Array.from()` and then accesses the elements using the array's indexing syntax.

**Pros and Cons**

**Direct Access (`[]` notation)**

Pros:

* Typically faster, as it avoids the overhead of creating a new array
* More straightforward to implement

Cons:

* May not be suitable for all scenarios, such as when working with larger arrays or complex data structures
* Can lead to index out-of-bounds errors if not used carefully

**Array.from()**

Pros:

* More robust and safer, as it checks for bounds and avoids potential errors
* Can be useful in scenarios where the array needs to be converted to another data structure

Cons:

* Typically slower than direct access due to the overhead of creating a new array
* May incur additional memory allocations or copies

**Library Considerations**

The `Array.from()` method uses the following libraries:

1. Native JavaScript: Provides the `Array.from()` method, which converts an iterable object (in this case, `Uint8Array`) to an array.
2. DOM and Web APIs: If used in a web context, `Array.from()` may rely on additional libraries or frameworks for compatibility.

**Special JS Features/Syntax**

None mentioned in the provided benchmark code. However, it's worth noting that some JavaScript features, such as async/await, may be used in more complex scenarios or future optimizations.

**Alternative Approaches**

Other approaches to accessing elements in a `Uint8Array` might include:

1. Using a custom loop or iterator to iterate over the array
2. Utilizing specialized libraries or tools for working with binary data (e.g., WebAssembly)
3. Employing optimization techniques, such as caching or memoization, for specific use cases

Keep in mind that these alternatives may not be relevant to this specific benchmark and should be evaluated on a case-by-case basis.

The provided benchmark provides valuable insights into the performance differences between direct access and using `Array.from()` for accessing elements in a `Uint8Array`. By understanding these trade-offs, developers can make informed decisions about which approach best suits their needs.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.82 Safari/537.36

Browser/OS: Chrome 93 on Linux

View result in a separate tab

Test name	Executions per second
Uint8Array index	6802.5 Ops/sec
Array.from array index	214.5 Ops/sec

Related benchmarks:

UInt8Array vs cast to array index access (version: 0)

Comparing performance of: Uint8Array index vs Array.from array index

Created: 3 years ago by: Guest

Jump to the latest result

Uint8Array index

Array.from array index

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):